Physical uplink shared channel configurations and occasions for handover procedures

Abstract

Methods, systems, and devices for wireless communications are described. A user equipment (UE) may identify physical uplink shared channel (PUSCH) configuration parameters to send a handover completion message at the end of a handover. A source cell may notify the UE of a handover via a handover command and the UE may acquire system information, and in some cases, a downlink message, from a target cell. The UE may identify a waveform configuration, numerology configuration, and/or modulation scheme using information from the handover command message, the system information, and/or the downlink message. The UE may also determine occasions for transmitting a PUSCH. For example, each occasion may include a set of time-frequency resources on which the PUSCH may be transmitted. The UE may send the handover completion message to the target cell via the PUSCH, during the one or more identified occasions, using the identified configuration parameters.

What is claimed is: 
     
       1. A method for wireless communications at a user equipment (UE), comprising:
 receiving, from a source cell, a handover command comprising an indication to perform a handover to a target cell; 
 receiving an indication of a numerology configuration for a physical uplink shared channel configuration for a handover completion message to be transmitted via a physical uplink shared channel, wherein the physical uplink shared channel configuration is based at least in part on receiving the handover command or downlink control information of the target cell; 
 selecting a numerology from a set of numerologies based at least in part on the indication of the numerology configuration, wherein the numerology comprises a subcarrier spacing for transmitting the handover completion message to the target cell; and 
 transmitting, to the target cell, the handover completion message in accordance with the selected numerology and via the physical uplink shared channel having the physical uplink shared channel configuration, the handover completion message indicating a completion of the handover to the target cell. 
 
     
     
       2. The method of  claim 1 , wherein receiving the indication of the numerology configuration for the physical uplink shared channel configuration comprises:
 receiving an uplink grant indicating resources for transmitting the handover completion message via the physical uplink shared channel, the uplink grant comprising an indication of the physical uplink shared channel configuration and one or more parameters including the numerology configuration. 
 
     
     
       3. The method of  claim 2 , further comprising:
 receiving, within the uplink grant, an indication of a waveform configuration for the physical uplink shared channel, wherein the one or more parameters include the waveform configuration; and 
 selecting a waveform from a set of waveforms based at least in part on the indication of the waveform configuration. 
 
     
     
       4. The method of  claim 2 , further comprising:
 receiving, within the uplink grant, an indication of a modulation scheme configuration for the physical uplink shared channel, wherein the one or more parameters include the modulation scheme configuration; and 
 selecting a modulation scheme from a set of modulation schemes based at least in part on the indication of the modulation scheme configuration. 
 
     
     
       5. The method of  claim 4 , wherein the modulation scheme comprises frequency-domain-based Pi/2 binary phase shift keying for a demodulation reference signal associated with the physical uplink shared channel or time-domain-based Pi/2 binary phase shift keying for the demodulation reference signal associated with the physical uplink shared channel, and wherein the indication of the modulation scheme configuration comprises one or more reserved bits within the uplink grant. 
     
     
       6. The method of  claim 2 , wherein receiving the uplink grant indicating the resources for transmitting the handover completion message via the physical uplink shared channel comprises:
 receiving, from the target cell, the downlink control information comprising the uplink grant. 
 
     
     
       7. The method of  claim 1 , further comprising:
 receiving, from the target cell, system information comprising an indication of a waveform configuration for the physical uplink shared channel; and 
 selecting a waveform from a set of waveforms based at least in part on the indication of the waveform configuration. 
 
     
     
       8. The method of  claim 1 , further comprising:
 determining a waveform of an active bandwidth part of the source cell; and 
 selecting the waveform of the active bandwidth part for the physical uplink shared channel. 
 
     
     
       9. The method of  claim 1 ,
 wherein the numerology comprises a numerology of an initial uplink bandwidth part for the physical uplink shared channel. 
 
     
     
       10. The method of  claim 1 ,
 wherein the numerology comprises a numerology of an active uplink bandwidth part for the physical uplink shared channel. 
 
     
     
       11. The method of  claim 1 , further comprising:
 receiving an uplink grant indicating resources for transmitting the handover completion message via the physical uplink shared channel; and 
 selecting one or more parameters for the physical uplink shared channel configuration based at least in part on a determination that an indication of the one or more parameters for the physical uplink shared channel configuration is absent from the uplink grant, the one or more parameters for the physical uplink shared channel configuration comprising at least one of the numerology configuration, a waveform configuration, or a modulation scheme configuration. 
 
     
     
       12. The method of  claim 11 , further comprising:
 selecting a waveform from a set of waveforms based at least in part on receiving the indication of the one or more parameters in system information from the target cell, the indication of the one or more parameters comprising an indication of the waveform configuration; wherein selecting the waveform is based at least in part on the indication of the one or more parameters for the physical uplink shared channel configuration being absent from the uplink grant. 
 
     
     
       13. The method of  claim 11 , further comprising:
 determining a waveform of an active bandwidth part of the source cell; and 
 selecting the waveform of the active bandwidth part for the physical uplink shared channel, wherein selecting the waveform is based at least in part on the indication of the one or more parameters for the physical uplink shared channel configuration being absent from the uplink grant. 
 
     
     
       14. The method of  claim 11 , further comprising:
 selecting the numerology from the set of numerologies based at least in part on receiving the indication of the one or more parameters in system information received from the target cell, the indication of the one or more parameters comprising an indication of the numerology configuration, wherein selecting the numerology is based at least in part on the indication of the one or more parameters for the physical uplink shared channel configuration being absent from the uplink grant. 
 
     
     
       15. The method of  claim 11 , further comprising:
 determining a numerology of an active bandwidth part of the source cell; and 
 selecting the numerology of the active bandwidth part for the physical uplink shared channel, wherein selecting the numerology is based at least in part on the indication of the one or more parameters for the physical uplink shared channel configuration being absent from the uplink grant. 
 
     
     
       16. An apparatus for wireless communications at a user equipment (UE), comprising:
 a processor, memory coupled with the processor; and 
 instructions stored in the memory and executable by the processor to cause the apparatus to:
 receive, from a source cell, a handover command comprising an indication to perform a handover to a target cell; 
 receive an indication of a numerology configuration for a physical uplink shared channel configuration for a handover completion message to be transmitted via a physical uplink shared channel, wherein the physical uplink shared channel configuration is based at least in part on receiving the handover command or downlink control information of the target cell; 
 select a numerology from a set of numerologies based at least in part on the indication of the numerology configuration, wherein the numerology comprises a subcarrier spacing for transmitting the handover completion message to the target cell; and 
 transmit, to the target cell, the handover completion message in accordance with the selected numerology and via the physical uplink shared channel having the physical uplink shared channel configuration, the handover completion message indicating a completion of the handover to the target cell. 
 
 
     
     
       17. The apparatus of  claim 16 , wherein the instructions to receive the indication of the numerology configuration for the physical uplink shared channel configuration are executable by the processor to cause the apparatus to:
 receive an uplink grant indicating resources for transmitting the handover completion message via the physical uplink shared channel, the uplink grant comprising an indication of the physical uplink shared channel configuration and one or more parameters including the numerology configuration. 
 
     
     
       18. The apparatus of  claim 17 , wherein the instructions are further executable by the processor to cause the apparatus to:
 receive, within the uplink grant, an indication of a waveform configuration for the physical uplink shared channel, wherein the one or more parameters include the waveform configuration; and 
 select a waveform from a set of waveforms based at least in part on the indication of the waveform configuration. 
 
     
     
       19. The apparatus of  claim 17 , wherein the instructions are further executable by the processor to cause the apparatus to:
 receive, within the uplink grant, an indication of a modulation scheme configuration for the physical uplink shared channel, wherein the one or more parameters include the modulation scheme configuration; and 
 select a modulation scheme from a set of modulation schemes based at least in part on the indication of the modulation scheme configuration. 
 
     
     
       20. The apparatus of  claim 19 , wherein:
 the modulation scheme comprises frequency-domain-based Pi/2 binary phase shift keying for a demodulation reference signal associated with the physical uplink shared channel or time-domain-based Pi/2 binary phase shift keying for the demodulation reference signal associated with the physical uplink shared channel, and 
 the indication of the modulation scheme configuration comprises one or more reserved bits within the uplink grant. 
 
     
     
       21. The apparatus of  claim 17 , wherein the instructions to receive the uplink grant indicating the resources for transmitting the handover completion message via the physical uplink shared channel are executable by the processor to cause the apparatus to:
 receive, from the target cell, the downlink control information comprising the uplink grant. 
 
     
     
       22. The apparatus of  claim 16 , wherein the instructions are further executable by the processor to cause the apparatus to:
 receive, from the target cell, system information comprising an indication of a waveform configuration for the physical uplink shared channel; and 
 select a waveform from a set of waveforms based at least in part on the indication of the waveform configuration. 
 
     
     
       23. The apparatus of  claim 16 , wherein the instructions are further executable by the processor to cause the apparatus to:
 determine a waveform of an active bandwidth part of the source cell; and 
 select the waveform of the active bandwidth part for the physical uplink shared channel. 
 
     
     
       24. The apparatus of  claim 16 ,
 wherein the numerology comprises a numerology of an initial uplink bandwidth part for the physical uplink shared channel. 
 
     
     
       25. The apparatus of  claim 16 , wherein
 the numerology comprises a numerology of an active uplink bandwidth part for the physical uplink shared channel. 
 
     
     
       26. The apparatus of  claim 16 , wherein the instructions are further executable by the processor to cause the apparatus to:
 receive an uplink grant indicating resources for transmitting the handover completion message via the physical uplink shared channel; and 
 select one or more parameters for the physical uplink shared channel configuration based at least in part on a determination that an indication of the one or more parameters for the physical uplink shared channel configuration is absent from the uplink grant, the one or more parameters for the physical uplink shared channel configuration comprising at least one of the numerology configuration, a waveform configuration, or a modulation scheme configuration. 
 
     
     
       27. An apparatus for wireless communications at a user equipment (UE), comprising:
 means for receiving, from a source cell, a handover command comprising an indication to perform a handover to a target cell; 
 means for receiving an indication of a numerology configuration for a physical uplink shared channel configuration for a handover completion message to be transmitted via a physical uplink shared channel, wherein the physical uplink shared channel configuration is based at least in part on receiving the handover command or downlink control information of the target cell; 
 means for selecting a numerology from a set of numerologies based at least in part on the indication of the numerology configuration, wherein the numerology comprises a subcarrier spacing for transmitting the handover completion message to the target cell; and 
 means for transmitting, to the target cell, the handover completion message in accordance with the selected numerology and via the physical uplink shared channel having the physical uplink shared channel configuration, the handover completion message indicating a completion of the handover to the target cell. 
 
     
     
       28. A non-transitory computer-readable medium storing code for wireless communications at a user equipment (UE), the code comprising instructions executable by a processor to:
 receive, from a source cell, a handover command comprising an indication to perform a handover to a target cell; 
 receive an indication of a numerology configuration for a physical uplink shared channel configuration for a handover completion message to be transmitted via a physical uplink shared channel, wherein the physical uplink shared channel configuration is based at least in part on receiving the handover command or downlink control information of the target cell; 
 select a numerology from a set of numerologies based at least in part on the indication of the numerology configuration, wherein the numerology comprises a subcarrier spacing for transmitting the handover completion message to the target cell; and 
 transmit, to the target cell, the handover completion message in accordance with the selected numerology and via the physical uplink shared channel having the physical uplink shared channel configuration, the handover completion message indicating a completion of the handover to the target cell.